Sidebar mechanisms found in cylinder locks include a sidebar that spans across the shear line of the cylinder and blocks the rotation of the plug relative to the shell. Such sidebar mechanisms usually perform their locking function in any of a number of ways. First, the sidebars can be biased outwardly from the plug and are forced inwardly by the rotation of the plug acting on an exterior sloping surface (see U.S. Pat. No. 167,088 Felter), or second, the sidebars can be biased inwardly towards detainers in the plug, and a sloping surface on the interior of the sidebar is forced outwardly by the stronger bias of the detainers (see U.S. Pat. No. 1,965,336 FitzGerald).
In the context of this disclosure, when used to describe a sidebar, the term “inner,” “interior,” or “inwardly” refers to a radially inner or interior surface, side, end, edge, portion, or direction of the sidebar relative to the axis of rotation of the plug, or cylinder, of the lock, and the term “outer,” “exterior,” or “outwardly” refers to a radially outer or exterior surface, side, end, edge, portion, or direction of the sidebar relative to the axis of rotation of the cylinder lock.
Sidebars that are biased outwardly usually have sloping edges on their exterior surface and straight edges on their interior surface so that the detainers have to be precisely aligned for the sidebar to fit into the unlocking position. Sidebars that are biased inwardly usually have a sloping surface on their interior surface, and straight or undercut blocking edges on their exterior so that rotation on the plug does not force the sidebar into further contact with the detainers. Additionally, a third type of sidebar can act to bind the detainers as the plug starts to rotate so that the detainers can no longer be manipulated into an unlocking position (see U.S. Pat. No. 3,722,241 Sussina). Other sidebars have a full round cross sectional shape or have beveled surfaces on both their interior and exterior edges (see U.S. Pat. No. 3,623,345 Solitanner). The round or beveled edges on these sidebars allow for return motion of the key to force the sidebar out across the shear line and relock the cylinder without additional biasing methods.
U.S. Pat. No. 2,629,247 to Deutsch describes a cylinder having two sidebars, one on each side of the plug. Both sidebars 19, 19a have beveled surfaces on their exterior edges and are urged outwardly by split ring springs 26. The sidebar on one side of the plug reads the tumbler as the plug starts to turn one direction (clockwise), and the sidebar on the other side of the plug reads the tumbler as the plug turns the other direction (counter clockwise). The reading of the tumblers by the sidebars is performed as the plug is turned, and one of the downward and inwardly sloping cam surfaces 29 located on the interior of the shell moves the adjacent sidebar inwardly. Both sidebars have similar detainer-reading functions and both are spring-biased outwardly.
U.S. Pat. No. 2,660,876 to Spain describes a cylinder that uses a sidebar mechanism constructed of two rods 29, 30 spring-loaded inwardly, whereby if the plug 21 is turned without having the tumbler 18 aligned correctly, the outer sidebar rod 30 moves into a widened portion 24a of the sidebar cavity in the plug and limits the plug from turning any further. When the rod 30 is moved to a binding position, most of the force applied to rotate the plug further is directed to the widened portion of the sidebar cavity and not against the detainers.
While Spain illustrates a dual-piece sidebar mechanism, it lacks a two piece sidebar as having separate binding and testing members that operate sequentially to bind and then test the tumblers.
U.S. Pat. No. 3,990,282 to Sorum describes a cylinder that uses a multi-piece sidebar to engage with flat sliding tumblers 27 that move from side to side in the cylinder. The multi-piece sidebar has an outer portion (locking block 37) that is biased outwardly by springs 40 and moves towards the tumblers as the plug is rotated, causing the tumblers to bind at a side to side location. The sidebar also has an inner portion (release tongue 43) that is spring-loaded 47 away from the tumblers and is forced towards the tumblers as the plug is turned. The tongue 43 has a thin edge 45 that must enter into a square opening (release slot 51) in the tumblers for the cylinder to be unlocked.
The lock of Sorum lacks an inwardly-biased testing sidebar having a beveled interior edge that contacts a beveled surface on the detainer.
U.S. Pat. No. 6,755,063 to Takadama describes a changeable cylinder with a sidebar 22 biased outwardly and located inside a sidebar holder 19. Rotation of the plug moves the sidebar holder to a position aligned with a receiving slot in the shell, and the sidebar holder can move outwardly to allow the tumblers to be realigned to a new combination. The sidebar moves into the tumblers when they are aligned by the correct key so that the sidebar-engaging concave portion 12 is in the opening position. Rotation of the plug forces the sidebar front end portion 23 out of the receiving slot in the shell and forces the sidebar into the sidebar engaging concave portion 12 in the tumbler.
The outer portion of the sidebar mechanism of Takadama with the beveled edge that surrounds the two sides of the sidebar is actually a compression member that keeps the changeable detainers coupled together after they have been set to a new combination. It does not provide any sidebar function of unlocking or binding.
U.S. Pat. No. 4,815,307 to Widen describes (for example, in FIG. 17 and others) a cylindrical pin 23 with a projecting finger 57 that has a substantially beveled surface (57′, 57″, 57′″) designed to contact the bitting on a key. As shown in FIG. 12 of Widen, the pins also have a hollow cavity at the other end of the pin that accepts a spring to bias the pin against the key. This pin interacts with a sidebar locking device at the back side of the cylindrical body 39a.
U.S. Pat. No. 6,427,506 to Praunbauer describes a cylinder that incorporates finger pins 10 with body 5 of a rectangular shape and a finger like projection 9 with a beveled surface 29 for contact with the key bitting surface. Additionally the finger pins have a projection 17 for contacting an external spring and a notch 11 for sidebar interface. The cylinder uses a sidebar 6 that is spring loaded 24 outwardly. Sidebar legs 12 contact the finger pins, and when correctly aligned, these legs fit into the notches 11.